Konica C8000 (Printing on Uncoated)

Just bought a C8000 and have it on my floor running and I'm a bit disappointed about the way the machine prints on a UN-coated or wove sheet. Is there a trick on the digital presses as to how to get the toner to adhere to the sheet better. Its not coming off the sheet it just has horrible mid-tone issues. I have started with changing fuser temps and machine speed but haven't really seen that big of a difference. just wondered if i could get some knowledgeable people to give me a few ideas. Also is this a problem for all digital presses or just the C8000 of course all the samples I saw prior to my purchase didn't look like this.